All-ceramic lead-free percolative composite with a colossal dielectric response

✍ Scribed by Vid Bobnar; Marko Hrovat; Janez Holc; Marija Kosec

• Book ID: 104022968
• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 418 KB
• Volume: 29
• Category: Article
• ISSN: 0955-2219
• DOI: 10.1016/j.jeurceramsoc.2008.07.023

✦ Synopsis

All-ceramic lead-free percolative composite, comprising RuO 2 with high electrical conductivity denoted as the conductive phase and ferroelectric (K, Na)NbO 3 ceramics, was developed. Structural analysis revealed a uniform distribution of conductive ceramic grains within the ceramic matrix. Consequently, the dielectric response in the (K, Na)NbO 3 -RuO 2 composite follows the predictions of the percolation theory. Thus, close to the percolation point exceptionally high values of the dielectric constant were obtained-values as high as 20,000 were detected at room temperature at 1 kHz. Fit of the data, obtained for samples of different compositions, revealed critical exponent and percolation point, which reasonably agree with the theoretically predicted values.